Unhairing process



Patented Jan. 21, 1941 UNHAIRHNG ranches Wilhelm Neugehauer, Wiesbaden-Blebrich, Germany, assignor to Kalle a Ca. Aktiengesellschait, Wiesbaden-Biebrich, Germany No Drawing. Application June 22, 1938, Serial No. 215,238. In Germany June 29, 1937 4 Claims.

The present invention relates 'to unhairing processes.

It isknown to use sulphites for unhairing hides or skins. These bodies are used in combination 5 with lime or other substance of alkaline reaction which has been applied either simultaneously with the sulphite or in a subsequent operation on the hide. It is also known to use the sulphites in combination. with enzymes in the unhairing l process.

The unhairing process of the present invention treats the hide or skin simultaneously or successively with a sulphite preferably an alkali metal sulphite and a suitable enzyme in aqueous solum tion. It has been found that the activity of the sulphite in this process can be enhanced by simultaneous use oi a salt of a heavy metal. If, for example, softened felts are handled first with a sulphite solution containing an addition of a 20 copper salt, and finally with a solution of a proteolytic enzyme the unhairing operation is easier than in the absence of the copper salt. The same unhairing eii'ect can be'produced in a shorter time or with a smaller proportion of enzyme in 55 consequence of the presence of thecopper salt. Somewhat small proportions of copper salt sufiice for this purpose. Considerable efiects are obtained, for example, when the treating liquor contains only 1 part of copper sulphate per 10,000 0 parts. Other heavy metal salts besides the copper salts aifect the unhairing in the manner described, although the action of the various heavy metals is not equally powerful. Mercury salts come first in this matter. Silver salts may also 5 be used. Also mixtures of several metal salts may be employed.

It is advantageous to use the heavy metal salt in the presence of a substance capable of forming a complex salt with the heavy metal salt or an 0 other substance which retains the metal salt in solution at a hydrogen-ion concentration whereat there would otherwisebe precipitated an insoluble metal compound. Such substances are, for instance, albuminous bodies, amino acids, oxy 5 acids, thiourea, pyrophosphates, nitrilotriacetic acid or the like. There may also be used directly complex salts of heavy metals. I As enzymes especially proteolytic enzymes obtained with the aid of bacteria or fungi may be J used. Also pancreatic enzymes are suitable.

It is possible according to the invention to treat the hides or skins first with the solution of the sulphite containing the heavy metal salt and to treat them in a subsequent operation with the 5 enzyme in the same bath or preferably after rinsing in a separate bath. In many cases it may also be practical to add the enzyme at the beginning of the operation to the solution containing the sulphite and the heavy metal salt. This manner of operation is, however, less recommended. Since many enzymes are very sensitive to traces of heavy metals it may be preferable to use an addition which protects the enzyme against poisoning by metal, when enzymes and heavy metal salts are simultaneously present.

The enzyme solution is adjusted to a suitable pH value in known nner. Its temperature. may vary within somewhat Wide limits, for example, between about 5 and 30 C. In general the operation is best conducted at room tem perature. The described pretreatment with a solution free fromenzymes may be conducted at the same temperature.

r The following examples illustrate the inven tion:

(1) Soaked calf skins or skins oi other animals are handled for 20 hours at about 20 C. in a solution of kg. of sodium sulphlte, 10 kg. of sodium bicarbonate, .3 kg. of copper sulphate and 4 kg. of :peptone per 1000 1. water. For preven- 7 tion of putrefaction, .l per cent of an active disinfectant, for example one prepared according to U. S. Patent 1,919,298 and known by the Trade- Mark Preventol fll may be added to the solu-- tion. The skins are then rinsed for a short time 30 and then left for about 20 hours in a bath at 20 C. and of the following composition: .7 kg. of a commercial enzyme preparation from Bacillus.

- mesentericus, 10 kg. of sodium bicarbonate, 1 kg.

of Preventol ill and 1000 l. of water. The

skins are then freed from hair. Instead of the peptone there may be used 10 kg. of aqueous am- ,monia solution of per cent strength, or there may be substituted for the peptone a suitable amino acid, an amine, a salt of an oxy acid or M thiourea; if desired this complex forming substance may be omitted. it is possible to treat about 100 kg. of skins with the descrl soluions.

(2) Soaked calf sldns are treated for hours at room temperature with a solution of 10 ire. of sodium sulphite, 10 of sodium bicarbonate, 3 lie. of sodium nitrilotriacetate and .2 lea. oi cop sulphate in 1.0001. of Water to which has been added about .1 per cent of Preventol fill. the sulphite bath the skins are rinsed for a short time and then immersed in an enzyme bath at 22 C. and of the following composition: .1 is .of pancreatin. 10 kg. or sodium bicarbonate, 1 kg. oi Preventol ill and 10001.0? ter. The skins.

After (3) Soaked calf skins are handled for 20 hours at room temperature in 500 '1. of water containing kg. of sodium sulphite, 5 kg. of sodium bicarbonate, .05 kg. of mercuricacetate and 1 kg. of sodium nitrilotriacetate. The skins are then rinsed and treated in a bath of the following composition: 500 l. of water, 5 kg. of sodium bicarbonate, .3 kg. of tryptase from Bacillus mesentericus and .2 kg. of thymol. The skins remain in this bath for about 15 hours.

(4) Soaked goat skins are handled for hours at 20-25 C. in a solution of 10 kg. of sodium sulphite, 5 kg. of sodium bicarbonate,-3 kg. of sodium nitrilotriacetate and .3 kg. of copper sulphate in 1000 1. of water. The skins are then rinsed and transferred to an enzyme bath consisting of a solution of 1kg. of a commercial proteinase preparation from Bacillus mesentricus and 5 kg. of sodium bicarbonate in 500 l. of water.

(5) Soaked calf skins are treated for about 20-30 hours with a solution at 20-25 C. of 10 kg. of sodium sulphite, 10 kg. of sodium bicarbonate, 3 kg. of sodium nitrilotriacetate, .3 kg.

proteinase preparation from Bacillus mesentericus in 1000 l. of water.

(6) The operation is conducted as described in Example 5, but instead of .3 kg. of copper sulphate .4 kg. of mercuric sulphate is used. Silver nitrate may also be used as the heavy metal compound.

(7) Soaked calf skins are treated for 48 hours at about 25 C. with'a solution of 6 kg. oi potasslum sulphite, 3 kg. of sodium bicarbonate, .1 kg.

of mercuric chloride and .5 kg. of a disinfecting means in 500 1. of water. The skins are rinsed for half an hour and then handled for 24 hours at about 25 C. in a bath containing .5 kg. of sodium bicarbonate, .25 kg. of a commercial enzyme preparation from Bacillus mesenterz'cus and .5 kg. of a disinfecting means in 500 1. of

water.

(8) Soaked calf skins are reated for 48 hours v at about 25 C. with a solution consisting of 3 kg.

of sodium sulphite, 3 kg. of sodium bicarbonate, .15 kg. of silver nitrate, .5 kg. of a disinfecting means and 500 l. of water. After rinsing the skins are treated for 24 hours .at about 25-30 C.

of copper sulphate and 1 kg. of a commercial with a solution of 1 kg. of sodium bicarbonate,.5

kg. of a disinfecting means and .25 kg. of an enzyme preparation from Bacillus subtilis in 500 1. of water.

(9) Soaked calf skins or goat skins are handled for 24 hours at about 25 C. in a solution which consists of '3 kg. of sodium sulphite, 3 kg. of sodium bicarbonate, .1 kg. of mercuric chloride, 1 kg. of sodium butylnaphthalinsulphonate, .5 kg of a disinfecting means and 500 1. of water. The skins are then rinsed and then treated for 48 hours at about 25 C. with a bath which contains 1 kg. sodium bicarbonate, .1 kg. of pancreas preparation and .5.kg. of a disinfecting means in 500 l. of water.

(10) Soaked sheep skins are coated on the meat side with the equal weight of the following lime cream which contains 20% of wood flour as a thickening means: 100 1. of water, 1.2 kg. of sodium sulphite, 1.2 kg. of sodium bicarbonate, .08 kg. of mercuric chloride. 1.5 kg. of potash soap, .35 kg. of a disinfecting means and .35 kg. of an enzyme preparation from Bacillus mesentericus. The skins are laid with their meat sides one upon another and remain lying for 48 hours at about 20-25" C.

I claim:

1. An unhairing process which comprises treating a hide or skin with an aqueous solution containing a water-soluble sulphite and a watersoluble salt of a metal selected from the group consisting of mercury, silveruand copper and with an aqueous solution containing a proteolytic enzyme.

2. An unhairing process according to claim 1 wherein the said heavy metal salt is a complex salt.

3. An unhairing process which comprises treating a hide or skin with an aqueous solution containing an alkali metal sulphite and a watersoluble complex salt of a metal selected from the group consisting of mercury, silver and copper and with an aqueous solution containing a proteolyticenzyme.

4. An unhairing process which comprises treating a hide or skin with an aqueous solution containing .a water-soluble sulphite and a water-soluble salt of a metal selected from the group consisting of mercury, silver and copper and treating the said hide or skin in a subsequent operation with an aqueous solution containing .a proteolytic enzyme.

WILHEIM NEUGEBAUER. 

